Neurocognitive impairments and brain abnormalities resulting from opioid-related overdoses: A systematic review

Overdose Risk and Brain Injury (Traumatic Brain Injury/Acquired Brain Injury), A Commentary

OBJECTIVE

This commentary seeks to evaluate existing knowledge about the relationship between brain injury (BI) and overdose (OD), to unify distant bodies of literature, and to enhance prevention and treatment for opioid OD among individuals with BI.

BACKGROUND

There is a hidden epidemic of undiagnosed BI in the United States. Due to lack of screening, the vast majority of BI sufferers do not know they have a BI. Not only are those with BI at elevated risk for opioid use, misuse, and opioid use disorder, but also they are at elevated risk for OD. Conversely, those with OUD and those who experienced an OD, are more likely to sustain BI. Key Findings/Conclusions: The existing literature suggests that primary strategies to reduce ABI (Acquired Brain Injury)/TBI (Traumatic Brain Injury) harms involve addressing: screening, stigma, racial disparities, and popular misconceptions about OD. The association between TBI and OD is an underexamined public health issue, exacerbated by the bidirectional nature of the relationship. Not only is TBI a risk factor for opioid OD; opioid OD was also found to be a major cause of ABI, which can have lifelong effects similar to Alzheimer's disease. Screening tools for BI were underutilized and inconsistently implemented across reviewed studies. Enhanced screening population wide is a promising intervention, complemented with expanded treatment and research. Black individuals face worse outcomes in BI and treatment outcomes. Anti-racist strategies must fight inequity while addressing social and structural drivers of overdose and BI within the opioid and opioid overdose crises.

Inverse pattern of GABAergic system impairment in the external versus internal globus pallidus in male heroin addicts

Opioid addiction is a global problem that has been exacerbated in the USA and Europe by the COVID-19 pandemic. The globus pallidus (GP) plays a prominent neurobiological role in the regulation of behaviour as an output station of the striato-pallidal system. GABAergic large projection neurons are the main neuronal type in the external (EGP) and internal (IGP) parts of the GP, where addiction-specific molecular and functional abnormalities occur. In these neurons, glutamate decarboxylase (GAD) with isoforms GAD 65 and 67 is a key enzyme in GABA synthesis, and experimental studies suggest GAD dysregulation in the GP of heroin addicts. Our study, which was performed on paraffin-embedded brains from the Magdeburg Brain Bank, aimed to investigate abnormalities in the GABAergic function of large GP neurons by densitometric evaluation of their GAD 65/67-immunostained thick dendrites. The study revealed a bilaterally decreased fibres density in the EGP paralleled by the increase in the IGP in 11 male heroin addicts versus 11 healthy controls (significant U-test P values). The analysis of confounding variables found no interference of age, brain volume, and duration of formalin fixation with the results. Our findings suggest a dysregulation of GABAergic activity in the GP of heroin addicts, which is consistent with experimental data from animal models and plays potentially a role in the disturbed function of basal ganglia circuit in opioid addiction.

Fact vs. fiction: naloxone in the treatment of opioid-induced respiratory depression in the current era of synthetic opioids

Opioid-induced respiratory depression (OIRD) deaths are ~80,000 a year in the US and are a major public health issue. Approximately 90% of fatal opioid-related deaths are due to synthetic opioids such as fentanyl, most of which is illicitly manufactured and distributed either on its own or as an adulterant to other drugs of abuse such as cocaine or methamphetamine. Other potent opioids such as nitazenes are also increasingly present in the illicit drug supply, and xylazine, a veterinary tranquilizer, is a prevalent additive to opioids and other drugs of abuse. Naloxone is the main treatment used to reverse OIRD and is available as nasal sprays, prefilled naloxone injection devices, and generic naloxone for injection. An overdose needs to be treated as soon as possible to avoid death, and synthetic opioids such as fentanyl are up to 50 times more potent than heroin, so the availability of new, higher-dose, 5-mg prefilled injection or 8-mg intranasal spray naloxone preparations are important additions for emergency treatment of OIRDs, especially by lay people in the community. Higher naloxone doses are expected to reverse a synthetic overdose more rapidly and the current formulations are ideal for use by untrained lay people in the community. There are potential concerns about severe withdrawal symptoms, or pulmonary edema from treatment with high-dose naloxone. However, from the perspective of first responders, the balance of risks would point to administration of naloxone at the dose required to combat the overdose where the risk of death is very high. The presence of xylazines as an adulterant complicates the treatment of OIRDs, as naloxone is probably ineffective, although it will reverse the respiratory depression due to the opioid. For these patients, hospitalization is particularly vital. Education about the benefits of naloxone remains important not only in informing people about how to treat emergency OIRDs but also how to obtain naloxone. A call to emergency services is also essential after administering naloxone because, although the patient may revive, they may overdose again later because of the short half-life of naloxone and the long-lasting potency of fentanyl and its analogs.

Cognitive impairment as a predictor of long-term psychological distress in patients with polysubstance use disorders: a prospective longitudinal cohort study

BACKGROUND

The association between polysubstance use disorder (pSUD), mental illness, and cognitive impairments is well established and linked to negative outcomes in substance use disorder treatment. However, it remains unclear whether cognitive impairment predicts long-term psychological distress among treatment seeking patients with pSUD. This study aimed to investigate the associations and predictive ability of cognitive impairment on psychological distress one and 5 years after treatment initiation.

METHODS

N = 164 treatment seeking patients with pSUD were sampled at treatment initiation. We examined associations between cognitive impairment according to Montreal Cognitive Assessment® (MoCA®), Wechsler Abbreviated Scale of Intelligence (WASI), and Behaviour Rating Inventory of Executive Function - Adult version (BRIEF-A) administered at treatment initiation and psychological distress defined by the Symptom Check List-90-Revised (SCL-90-R) at treatment initiation, one and five years later. We ran hierarchical logistic regressions to assess the predictive ability of the respective cognitive instruments administered at treatment initiation on psychological distress measured one and five years later including psychological distress at treatment initiation and substance intake at the time-points of the measurements as covariates.

RESULTS

The main results was that MoCA® and BRIEF-A predicted psychological distress at years one and five, but BRIEF-A lost predictive power when accounting for psychological distress at treatment initiation. WASI predicted psychological distress at year one, but not at year five.

CONCLUSIONS

Results from MoCA® and WASI was found to be less sensitive to the effect of psychological distress than BRIEF-A. Cognitive impairment at treatment initiation may hold predictive value on later psychological distress, yet its clinical utility is uncertain.

Diagnosis of Delayed Post-Hypoxic Leukoencephalopathy (Grinker's Myelinopathy) with MRI Using Divided Subtracted Inversion Recovery (dSIR) Sequences: Time for Reappraisal of the Syndrome?

Background: Delayed Post-Hypoxic Leukoencephalopathy (DPHL), or Grinker's myelinopathy, is a syndrome in which extensive changes are seen in the white matter of the cerebral hemispheres with MRI weeks or months after a hypoxic episode. T2-weighted spin echo (T2-wSE) and/or T2-Fluid Attenuated Inversion Recovery (T2-FLAIR) images classically show diffuse hyperintensities in white matter which are thought to be near pathognomonic of the condition. The clinical features include Parkinsonism and akinetic mutism. DPHL is generally regarded as a rare condition. Methods and Results: Two cases of DPHL imaged with MRI nine months and two years after probable hypoxic episodes are described. No abnormalities were seen on the T2-FLAIR images with MRI, but very extensive changes were seen in the white matter of the cerebral and cerebellar hemisphere on divided Subtraction Inversion Recovery (dSIR) images. dSIR sequences may produce ten times the contrast of conventional inversion recovery (IR) sequences from small changes in T1. The clinical findings in both cases were of cognitive impairment without Parkinsonism or akinetic mutism. Conclusion: The classic features of DPHL may only represent the severe end of a spectrum of diseases in white matter following global hypoxic injury to the brain. The condition may be much more common than is generally thought but may not be recognized using conventional clinical and MRI criteria for diagnosis. Reappraisal of the syndrome of DPHL to include clinically less severe cases and to encompass recent advances in MRI is advocated.

Neuroimaging features of accidental fentanyl overdose in a toddler

The opioid epidemic has become a significant public health crisis worldwide. With the rise in popularity of fentanyl, opioid overdoses continue to rise at unprecedented rates. Unfortunately, young children have become collateral damage in the face of the opioid epidemic. Accidental exposures and ingestions are the leading cause of opioid overdose in this age group and can result in significant acute complications, long-term sequelae and even death. We present the case of a toddler with accidental fentanyl ingestion who experienced seizures and required intubation for respiratory distress. He was found to have notable diffusion restriction cerebellar changes on MRI and ultimately discharged with normal neurological function. Our case adds to the growing literature of the clinical presentation and neuroimaging features associated with opioid toxicity in young children.

Multinational appraisal of the epidemiological distribution of opioid fatalities: a systematic review and meta-analysis

Background

The global or multinational scientific evidence on the distribution of opioid fatality is unknown. Hence, the current study collects epidemiological characteristics to shed light on the ongoing global or multinational opioid crisis and to promote the development of public health prevention/management strategies.

Method

All documents on PRISMA standards were retrieved via electronic databases.

Results

Among the 47 articles relevant to our studies, which depict a total population size of 10,191 individuals, the prevalence of opioid fatal overdose was 15,022 (14.74%). Among the 47 articles, 14 of them reported the gender of the participants, with 22,125 (15.79%) male individuals and 7,235 (5.17%) female individuals, and the age distribution of the participants that was most affected by the overdose was as follows: 29,272 (31.13%) belonged to the 18-34-year-old age group and 25,316 (26.92%) belonged to the less than 18-year-old age group. Eighteen studies qualified for the meta-analysis of the multinational prevalence of fatal opioid overdose, depicting an overall pooled prevalence estimate of 19.66%, with 95% CIs (0.13-0.29), I2 = 99.76% determined using the random-effects model, and Q statistic of 7198.77 (p < 0.0001). The Egger test models of publication bias revealed an insubstantial level of bias (p = 0.015). The subgroup analysis of the study design (cohort or other) revealed that others have the highest prevalence estimate of 34.37, 95% CIs (0.1600-0.5901), I2 = 97.04%, and a sample size of less than 1,000 shows the highest prevalence of 34.66, 95% CIs (0.2039-0.5234), I2 = 97.82%, compared to that of more than 1,000 with a prevalence of 12.28, 95% CIs (0.0675-0.2131), I2 = 99.85%. The meta-regression analysis revealed that sample size (less-than or greater-than 1,000), (p = 0.0098; R2 = 3.83%) is significantly associated with the observed heterogeneity.

Conclusion

Research-based findings of fatal opioid overdose are grossly lacking in middle- and low-income nations. We established that there is a need for opioid fatality surveillance systems in developing nations.

LncRNAs and CircRNAs as Strategies against Pathological Conditions Caused by a Hypoxic/Anoxic State

Brain damage can be induced by oxygen deprivation. It is known that hypoxic or anoxic conditions can lead to changes in the expression levels of non-coding RNAs (ncRNAs), which, in turn, can be related to Central Nervous System (CNS) injuries. Therefore, it could be useful to investigate the involvement of non-coding RNAs (ncRNAs), as well as the underlying mechanisms which are able to modulate them in brain damage induced by hypoxic or anoxic conditions. In this review, we focused on recent research that associates these conditions with long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). The results of this review demonstrate that the expression of both lncRNAs and circRNAs can be influenced by oxygen deprivation conditions and so they can contribute to inducing damage or providing neuroprotection by affecting specific molecular pathways. Furthermore, several experimental studies have shown that ncRNA activity can be regulated by compounds, thus also modifying their transcriptomic profile and their effects on CNS damages induced by hypoxic/anoxic events.

Hippocampal volume loss in individuals with a history of non-fatal opioid overdose

Incidence of opioid-related overdoses in the United States has increased dramatically over the past two decades. Despite public emphasis on overdose fatalities, most overdose cases are not fatal. Although there are case reports of amnestic syndromes and acute injury to the hippocampus following non-fatal opioid overdose, the effects of such overdoses on brain structure are poorly understood. Here, we investigated the neuroanatomical correlates of non-fatal opioid overdoses by comparing hippocampal volume in opioid use disorder (OUD) patients who had experienced an opioid overdose (OD; N = 17) with those who had not (NOD; N = 32). Voxel-based morphometry showed lower hippocampal volume in the OD group than in the NOD group, which on post hoc analysis was evident in the left but not the right hippocampus. These findings strengthen the evidence that hippocampal injury is associated with non-fatal opioid overdose, which is hypothesized to underlie overdose-related amnestic syndrome.

A pilot study investigating cognitive impairment associated with opioid overdose

BACKGROUND

In 2021, while overdose (OD) deaths were at the highest in recorded history, it is estimated that >80% of ODs do not result in a fatality. While several case studies have indicated that opioid-related ODs can result in cognitive impairment, the possible association has not yet been systematically investigated.

METHODS

78 participants with a history of OUD who reported experiencing an OD in the past year (n=35) or denied a lifetime history of OD (n=43) completed this study. Participants completed cognitive assessments including the Test of Premorbid Functioning (TOPF) and the NIH Toolbox Cognition Battery (NIHTB-CB). Comparisons were made between those who experienced an opioid-related OD in the past year versus those who denied a lifetime OD history while controlling for factors including age, premorbid functioning, and number of prior ODs.

RESULTS

When comparing those who experienced an opioid-related OD within the past year to those without a history of OD, uncorrected standard scores were generally comparable; however, differences emerged in the multivariable model. Specifically, compared to those without a history of OD, those who experienced a past year OD evidenced significantly lower total cognition composite scores (coef. = -7.112; P=0.004), lower crystalized cognition composite scores (coef. = -4.194; P=0.009), and lower fluid cognition composite scores (coef. = -7.879; P=0.031).

CONCLUSIONS

Findings revealed that opioid-related ODs may be associated with, or contribute to, reduced cognition. Extent of the impairment appears contingent upon individuals' premorbid intellectual functioning and the cumulative number of past ODs. While statistically significant, clinical significance may be limited given that performance differences (∼4 - 8 points) were not particularly robust. More rigorous investigation is warranted, and future studies must also account for the many other variables possibly contributing to cognitive impairment.

Cost-effectiveness of flexible take-home buprenorphine-naloxone versus methadone for treatment of prescription-type opioid use disorder

BACKGROUND

Our objective was to examine the cost-effectiveness of flexible take-home buprenorphine-naloxone (BNX) versus methadone alongside the OPTIMA trial in Canada.

METHODS

The OPTIMA study was a pragmatic, open-label, noninferiority, two-arm randomized controlled trial, to assess the comparative effectiveness of flexible take-home BNX vs. methadone in routine clinical care for individuals with prescription-type opioid use disorder. We evaluated cost-effectiveness using a semi-Markov cohort model. Probabilities of overdose were calibrated, accounting for fentanyl prevalence and other overdose risk factors such as naloxone availability. We considered health sector and societal cost perspectives, including costs (2020 CAD) for treatment, health resource use, criminal activity, and health state-specific preference weights as outcomes to calculate incremental cost-effectiveness ratios. Six-month and lifetime (3% annual discount rate) time-horizons were explored.

RESULTS

Over a lifetime time horizon, individuals accumulated -0.144 [CI: -0.302, -0.025] incremental quality-adjusted life years (QALYs) in BNX compared with methadone. Incremental costs were -$2047 [CI: -$39,197, $24,250] from a societal perspective, and -$4549 [CI: -$6332, -$3001] from a health sector perspective. Over a six-month time-horizon, individuals accumulated 0.002 [credible interval (CI): -0.011, 0.016] incremental QALYs in BNX compared with methadone. Incremental costs were -$307 [CI: -$10,385, $8466] from a societal perspective and -$1111 [CI: -$1517, -$631] from a health sector perspective. BNX was dominated (costlier, less effective) in 49.7% of simulations when adopting a societal perspective over a lifetime time horizon.

CONCLUSIONS

Flexible take-home BNX was not cost-effective versus methadone over a lifetime time horizon, resulting from better treatment retention in methadone compared to BNX.

Drug and alcohol use disorders among adults with select disabilities: The national survey on drug use and health

BACKGROUND

Deaths caused by drugs and alcohol have reached high levels in the US, and prior research shows a consistent association between disability status and substance misuse.

OBJECTIVE

Using national data, this study quantifies the association between disability status and drug and alcohol use disorders among US adults.

METHODS

The most recent pre-pandemic years (2018-2019) of the cross-sectional National Survey on Drug Use and Health (n = 83,439) were used to examine how the presence of any disability, and specific disabilities, were associated with past year drug and alcohol use disorders. Logistic regression was used to estimate adjusted odds ratios (aORs) controlling for potential sociodemographic confounders.

RESULTS

Adults with any disability had increased odds of drug (aOR = 2.7; 95% CI = 2.5-3.0), and alcohol use disorder (aOR = 1.8; 95% CI = 1.6-2.0), compared to adults without disability. Examining specific types of disabilities, adults with cognitive limitations only had increased odds of drug (aOR = 3.1; 95% CI = 2.6-3.6), and alcohol use disorders (aOR = 2.2; 95% CI = 1.9-2.5), compared to adults without disability. Smaller associations were observed between vision and complex activity limitations and drug use disorder. Adults with two or more types of limitations had increased odds of drug (aOR = 3.7; 95% CI = 3.3-4.3), and alcohol use disorders (aOR = 2.3; 95% CI = 2.0-2.6).

CONCLUSIONS

The presence of disability, especially cognitive limitation only, or two or more types of limitations, is associated with elevated odds of drug and alcohol use disorder among US adults. Additional research should examine the temporal relationship between and mechanisms linking disability and substance misuse.

Association of Opioid and Stimulant Use Disorder Diagnoses With Fatal and Nonfatal Overdose Among People With a History of Incarceration

IMPORTANCE

Studies have suggested a rise in opioid- and stimulant-involved overdoses in recent years in North America. This risk may be acute for individuals who have had contact with the criminal justice system, who are particularly vulnerable to overdose risk.

OBJECTIVE

To examine the association of opioid and/or stimulant use disorder diagnoses with overdose (fatal and nonfatal) among people with histories of incarceration.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study, population-based health and corrections data were retrieved from the British Columbia Provincial Overdose Cohort, which contains a 20% random sample of residents of British Columbia. The analysis included all people in the 20% random sample who had a history of incarceration between January 1, 2010, and December 31, 2014. Outcomes were derived from 5-years of follow-up data (January 1, 2015, to December 31, 2019). Statistical analysis took place from January 2022 to June 2022.

EXPOSURES

Substance use disorder diagnosis type (ie, opioid use disorder, stimulant use disorder, both, or neither), sociodemographic, health, and incarceration characteristics.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) are reported from an Andersen-Gill model for recurrent nonfatal overdose events and from a Fine and Gray competing risk model for fatal overdose events.

RESULTS

The study identified 6816 people (5980 male [87.7%]; 2820 aged <30 years [41.4%]) with histories of incarceration. Of these, 293 (4.3%) had opioid use disorder only, 395 (6.8%) had stimulant use disorder only, and 281 (4.1%) had both diagnoses. During follow-up, 1655 people experienced 4026 overdoses including 3781 (93.9%) nonfatal overdoses, and 245 (6.1%) fatal overdoses. In adjusted analyses, the hazard of both fatal (HR, 2.39; 95% CI, 1.48-3.86) and nonfatal (HR, 2.45; 95% CI, 1.94-3.11) overdose was highest in the group with both opioid and stimulant use disorder diagnoses.

CONCLUSIONS AND RELEVANCE

This cohort study of people with a history of incarceration found an elevated hazard of fatal and nonfatal overdose among people with both opioid and stimulant use disorder diagnoses. This study suggests an urgent need to address the service needs of individuals who have had contact with the criminal justice system and who co-use opioids and stimulants.

Integrating Cognitive Dysfunction Accommodation Strategies into an HIV Prevention Session: A 2-Arm Pilot Feasibility Study

Cognitive dysfunction is prevalent among persons on medication for opioid use disorder (MOUD). This cognitive dysfunction has been shown to reduce HIV treatment engagement and medication adherence. We investigated the impact of integrating specific behavioral strategies into an HIV prevention session to accommodate cognitive dysfunction among people on MOUD. Patients on MOUD (n = 20) were randomized to one of two different HIV prevention conditions. The same HIV risk reduction content was presented to both conditions; however, the experimental condition had accommodation strategies integrated into the session. Participants completed a skills checklist at pre-, post-, and 2-week follow-up to examine the level of HIV risk reduction content learned and utilized over time. Participants in the experimental condition indicated high acceptability (95%) for the accommodation strategies. These participants also demonstrated greater improvement in the ability to properly clean a syringe, from pre- to post- (p < 0.02) and from pre- to follow-up (p < 0.02) when compared to participants in the standard condition. Results from this pilot study indicate that accommodation strategies improved participants’ ability to learn, retain, and utilize risk reduction skills over time. This foundation of research indicates a promising, innovative strategy to increase the ability for persons on MOUD to engage in HIV prevention behaviors.

Frequency of fatal and non-fatal overdoses and response to grief and loss among people who inject drugs: An unexplored dimension of the opioid overdose crisis

BACKGROUND

We investigated the relationship between overdose events and grief and loss responses among people who inject drugs.

METHODS

We conducted a cross-sectional, tablet-based survey with a convenience sample of people who inject drugs (n = 249) from four community-based harm reduction programs in Toronto in 2019. We examined the association between frequency and types of overdose events (own, witnessed, death of significant person) in the last 6 months with grief and loss responses, identified using latent class analysis.

RESULTS

Among respondents, 70 (48.6 %) reported 2 or more personal overdoses, 173 (79.5 %) witnessed 2 or more overdoses, and 69 (41.4 %) experienced overdose deaths of 2 or more significant persons in the last 6 months. We identified 2 latent classes with probability of membership of 38.6 % (95 % confidence interval [CI]=31.0, 46.7) for medium/low intensity of responses to grief/loss and 61.4 % (95 % CI= 53.3, 69.0) for severe responses to grief/loss. In adjusted Poisson regression models with robust standard error estimators, severe responses to grief/loss were associated with exposure to two or more own overdoses (prevalence ratio [PR] = 1.44; 95 % CI=1.12, 1.84, p-value=0.004), and having witnessed one (PR=2.09; 95 % CI=1.05, 4.15, p-value=0.04) or witnessed two or more overdoses (PR=2.25; 95 % CI=1.24, 4.09, p-value=0.008). Severe grief/loss responses were also more common in individuals exposed to all three types of overdose events (PR=2.42; 95 % CI=1.08, 5.41, p-value=0.03).

CONCLUSIONS

Cumulative overdose events were associated with severe responses to grief and loss. Bereavement interventions should consider the complex nature of grief and loss following overdoses.